It’s hard to imagine the new comedies from Michael J. Fox and Robin Williams being very good. Many years have passed since they were sitcom stars, and the nature of TV humor has changed; it has gotten less schmaltzy and more coolly ironic.

It’s also hard to imagine the new sitcoms from Fox and Williams, which premiere opposite each other on Thursday at 9, being deeply awful – especially Fox’s. Since Fox left his series, he has put in a few unforgettable guest stints on “The Good Wife,” “Rescue Me,” and “Curb Your Enthusiasm.”

Well, the shows are neither awful nor awesome, so there’s no easy answer here. Both begin their runs as boilerplate comedies that could either improve, given the right kind of nurturing, or quickly become unbearable.